[basex-talk] Re: Fwd: Re: [XQST0045] Annotation %method is in reserved namespace.

26 Mar 2026

      Hi Graydon,

A method could be described as a function item in a map with at least one parameter, which is “supposed to” reference the containing map. In this context, it does not matter if the function item is an anonymous function, a partially applied function, named function references or any other reference. For example, the following three functions could be called methods:

let $get := map:get(?, 'data')
let $map := {
  'data': 12,
  'get-data1': fn($map) { map:get($map, 'data') },
  'get-data2': map:get(?, 'data'),
  'get-data3': $get
}
return (
  $map =?> get-data1(),
  $map =?> get-data2(),
  $map =?> get-data3()
)

The current language design is lax enough that a processor has no way of determining whether a function is really a “method”. The following code succeeds, even though it makes no sense:

{ 'first': head#1 } =?> first()

Having said this, your question made me realize that the current version of the W3C draft doesn’t actually provide a proper definition of what is meant by “methods” in XQuery. This will probably need to be fixed.

Best,
Christian
________________________________________

Von: Graydon Saunders <graydonish@fastmail.com>
Gesendet: Donnerstag, 26. März 2026 13:46
An: Christian Grün; BaseX; Eliúd Santiago Meza y Rivera
Betreff: Re: [basex-talk] Re: Fwd: Re: [XQST0045] Annotation %method is in reserved namespace.

Hi Christian,

The version 13 docs have "In XQuery, functions are called methods if they are embedded in maps."

I think something like

declare variable $icc:componentMap as map(*) := map {
  'QR-code': icc:isQRcode#1,
  'appendix': icc:isAppendix#1,
  'backmatter': icc:isBackmatter#1,
....

wouldn't count because it's references, rather than embedded. (I think embedded = anonymous function definition in the map)

Right now that map gets used as

$icc:componentMap($elementName)($element)

to call a function based on which element it is to do something per-element-name to generate an ID component. (Sections have "Sec" prefixes, parts have "Part" prefixes, etc.)

I think the =?> operator doesn't provide a way to do this. The method arrow expects the data is ALSO in the map.

Am I wrong about that?

Thanks!
Graydon

On Thu, Mar 26, 2026, at 04:25, Christian Grün via BaseX-Talk wrote:
Dear Eliúd,

The syntax of method calls was changed in the 4.0 draft of the specification. The %method annotation was replaced by a "=?>" operator:

let $number := {
  'value': 1,
  'inc': fn { map:put(., 'value', ?value + 1) }
}
return $number =?> inc()

This is mostly syntactic sugar. In XQuery 3.1, the same code could have been written as:

let $number := map {
  'value': 1,
  'inc': function($map) { map:put($map, 'value', $map?value + 1) }
}
let $inc-function := $number?inc
return $inc-function($number)

The syntax of the newest version of BaseX is currently documented in the 13 branch of our Wiki [1,2]. Due to numerous changes in the spec, it is about time for a BaseX 13 release.

Hope this helps,
Christian

[1] https://docs.basex.org/main/XQuery_4.0#methods
[2] https://docs.basex.org/13/XQuery_4.0#methods

________________________________________
Von: Eliúd Santiago Meza y Rivera via BaseX-Talk <basex-talk@mailman.uni-konstanz.de<mailto:basex-talk@mailman.uni-konstanz.de>>
Gesendet: Donnerstag, 26. März 2026 03:06
An: BaseX
Betreff: [basex-talk] Fwd: Re: [XQST0045] Annotation %method is in reserved namespace.

I tested you suggestions and it's works, the last one with little variation:

let $number := {
  'value': 1,
  'inc': fn { map:put(., 'value', .?value + 1) }
}
return $number=?>inc()

I was testing 'cause I need to use values objects.

Thanks!!!!!
---------- Forwarded message ---------
From: Martin Honnen via BaseX-Talk <basex-talk@mailman.uni-konstanz.de<mailto:basex-talk@mailman.uni-konstanz.de><mailto:basex-talk@mailman.uni-konstanz.de<mailto:basex-talk@mailman.uni-konstanz.de>>>
Date: Wed, Mar 25, 2026 at 6:55 PM
Subject: [basex-talk] Re: [XQST0045] Annotation %method is in reserved namespace.
To: <basex-talk@mailman.uni-konstanz.de<mailto:basex-talk@mailman.uni-konstanz.de><mailto:basex-talk@mailman.uni-konstanz.de<mailto:basex-talk@mailman.uni-konstanz.de>>>

On 26/03/2026 01:12, Eliúd Santiago Meza y Rivera via BaseX-Talk wrote:
Hello,

I was testing the feature https://docs.basex.org/main/XQuery_4.0#methods, but the examples raise the error XQST0045

let $vector := {
  'x': 5,
  'y': 6,
  'sum': %method fn() { ?x + ?y }
}
return $vector =?> sum()

In the fiddle the variation

let $vector := {
  'x': 5,
  'y': 6,
  'sum': fn { ?x + ?y }
}
return $vector =?> sum()

works

let $number := {
  'value': 1,
  'inc': %method fn() { map:put(., 'value', ?value + 1) }
}
return $number?inc()

as does

let $number := {
  'value': 1,
  'inc': fn { map:put(., 'value', ?value + 1) }
}
return $number=?>inc()

Not sure about the state of the annotation %method

--
LSC Eliud Santiago Meza y Rivera